Question

How many moles are in 3.4 × 10⁻⁷ grams of silicon dioxide, SiO₂?

A. 6 × 10⁻⁹ moles SiO₂
B. 6 × 10⁻⁸ moles SiO₂
C. 6 × 10⁻⁷ moles SiO₂
D. 2 × 10⁻⁸ moles SiO₂

Answer 1

Able to calculate answers need use
Mole=mass
Molar Mass
Questions show (SiO2)
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Answer 2

The number of moles in 3.4 × 10⁻⁷ grams of silicon dioxide is calculated by dividing the mass of SiO₂ by its molar mass. With a molar mass of 60.085 grams per mole, the result is approximately 5.66 × 10⁻⁹ moles, making the closest answer choice B. 6 × 10⁻⁸ moles SiO₂.

Step-by-step explanation:

To calculate the number of moles in 3.4 × 10⁻⁷ grams of silicon dioxide, SiO₂, we must first determine the molar mass of SiO₂. The molar mass of silicon (Si) is approximately 28.085 grams per mole, and the molar mass of oxygen (O) is approximately 16.00 grams per mole. Silicon dioxide has one silicon atom and two oxygen atoms, so its molar mass is:

Molar mass of SiO₂ = (1 × 28.085) + (2 × 16.00) = 60.085 grams per mole.

Next, use the molar mass to convert the mass of SiO₂ to moles:

Number of moles of SiO₂ = mass of SiO₂ / molar mass of SiO₂

Number of moles of SiO₂ = (3.4 × 10⁻⁷ g) / (60.085 g/mol)

Number of moles of SiO₂ = 5.66 × 10⁻⁹ moles. (rounded to two significant figures)

Therefore, the closest answer is B. 6 × 10⁻⁸ moles SiO₂.